Work pallet positioning and fixing device

Abstract

A positioning and fixing device positions a work pallet in the vertical and horizontal directions relative to a base member via a ring member, and also restricts its rotation around the vertical axis. The base member has Z reference surfaces that can stop a lower end reference surface of the ring member and position it in the vertical direction, and a tapered male engagement portion whose horizontal cross section is formed as a regular polygon having a plurality of outwardly convex circular arcuate vertex portions and a plurality of side portions, and that reduces in diameter upwards. The ring member has a tapered female engagement portion that can engage with the tapered male engagement portion so that its lower end reference surface is in contact against the Z reference surfaces. A clamp mechanism for fixing the ring member to the base member is provided, and the side portions of at least one of the tapered female engagement portion and the tapered male engagement portion are adapted to engage in close contact with the other via elastic deformation.

The invention claimed is: 
     
       1. A work pallet positioning and fixing device comprising:
 a ring member that is provided to a work pallet; 
 a base member to which the ring member can engage from above; and 
 a clamp mechanism for fixing the ring member to the base member; and 
 wherein the base member positions the ring member with respect to the base member in a vertical direction and a horizontal direction and also restrains rotation of the ring member with respect to the base member about a vertical axis; 
 wherein the base member comprises a vertical axis, Z reference surfaces for stopping a lower end reference surface of the ring member to position the ring member in the vertical direction, and a tapered male engagement portion whose horizontal cross section is formed as a regular polygon that has a plurality of circular arcuate vertex portions that are convex outward and a plurality of side portions, and which reduces in diameter upwards, and the tapered male engagement portion is formed integrally with the base member; 
 wherein the ring member comprises a vertical axis and a tapered female engagement portion that is formed to be capable of engaging with the tapered male engagement portion so that the lower end reference surface comes into contact against the Z reference surfaces, and moreover whose horizontal cross section is formed as a regular polygon that has a plurality of circular arcuate vertex portions that are convex outward and a plurality of side portions, and the tapered female engagement portion is formed integrally with the ring member; 
 wherein the tapered female engagement portion is adapted to engage in close contact with the tapered male engagement portion, by elastic deformation in a radial direction of at least one of an external circumferential side wall portion of the tapered female engagement portion and the internal circumferential side wall portion of the tapered male engagement portion; 
 wherein the clamp mechanism comprises a hydraulic cylinder for clamping and a ball lock mechanism which is provided on the base member and the ring member; 
 wherein the ball lock mechanism comprises a barrel portion formed at an upper end portion of the base member and inserted into a circular aperture in the ring member; a plurality of ball reception holes formed in the barrel portion; a plurality of balls, each of which is held in one of the plurality of ball reception holes and is movable in the radial direction; a plurality of ball reception grooves formed on an internal circumferential portion of the upper end portion of the ring member, so as to correspond to the plurality of ball reception holes, wherein the plurality of ball reception grooves receives the plurality of balls; a circular plate member provided at an upper end portion of a piston rod of the hydraulic cylinder and disposed to slide freely up and down in the barrel portion; and a plurality of inclined portions for ball driving and a plurality of concave portions for ball retraction formed on an external circumferential portion of the circular plate member so as to correspond to the plurality of ball reception holes; and 
 wherein the tapered male engagement portion is positioned more to the radial interior than a conical surface that contains the plurality of balls and centers in the radial directions of the Z reference surfaces. 
 
     
     
       2. A work pallet positioning and fixing device according to  claim 1 , wherein the plurality of ball reception holes and the plurality of balls provided to the barrel portion of the base member are positioned so as to correspond to central portions of the plurality of side portions of the tapered male engagement portion. 
     
     
       3. A work pallet positioning and fixing device according to  claim 1  or  claim 2 , further comprising:
 an annular air chamber defined between the base member and the circular plate member, to which pressurized air is supplied; 
 a plurality of air nozzles that are formed in the barrel portion, so as to communicate with the air chamber; 
 a plurality of horizontal air nozzles for blowing air between the lower end reference surface and the Z reference surfaces; and 
 a plurality of air passages that supply pressurized air from the air chamber to the plurality of horizontal air nozzles. 
 
     
     
       4. A work pallet positioning and fixing device according to  claim 1 , wherein the ring member has an elastic deformation promoting portion that promotes elastic deformation thereof in the direction to increase a radius of the ring member, when the plurality of side portions of the tapered female engagement portion are engaged in close contact with the plurality of side portions of the tapered male engagement portion. 
     
     
       5. A work pallet positioning and fixing device according to  claim 4 , wherein the elastic deformation promoting portion comprises a plurality of circular arcuate grooves with lower ends open that are shaped as circular arcs in plan view and are formed on a wall portion that surrounds the tapered female engagement portion. 
     
     
       6. A work pallet positioning and fixing device according to  claim 4 , wherein the elastic deformation promoting portion comprises a plurality of circular arcuate grooves with upper ends open that are shaped as circular arcs in plan view and are formed on a wall portion that surrounds the tapered female engagement portion. 
     
     
       7. A work pallet positioning and fixing device according to  claim 4 , wherein the elastic deformation promoting portion comprises an annular groove with a lower end open that is formed on a wall portion that surrounds the tapered female engagement portion. 
     
     
       8. A work pallet positioning and fixing device according to  claim 7 , further comprising a plurality of slits on an annular wall more circumferentially internal than the annular groove, spaced at intervals in a circumferential direction and oriented in the radial direction. 
     
     
       9. A work pallet positioning and fixing device according to  claim 7 , wherein the elastic deformation promoting portion comprises an annular wall more circumferentially internal than the annular groove, and an annular groove that is formed flat in the vertical direction and adjacent to the annular groove. 
     
     
       10. A work pallet positioning and fixing device according to  claim 4 , wherein the elastic deformation promoting portion comprises a plurality of slits on a wall portion that surrounds the tapered female engagement portion, formed spaced at intervals in a circumferential direction and oriented in the radial direction. 
     
     
       11. A work pallet positioning and fixing device according to  claim 1 , wherein a plurality of positioning pins oriented vertically are provided to the base member, and a plurality of pin holes into which the positioning pins are inserted, are provided in the ring member. 
     
     
       12. A work pallet positioning and fixing device according to  claim 1 , further comprising a plurality of positioning pins oriented vertically are provided to the base member, and a plurality of pin holes or notched apertures into which the positioning pins are inserted are provided in the work pallet. 
     
     
       13. A work pallet positioning and fixing device according to  claim 1 , wherein the regular polygon that is the horizontal cross section of the tapered male engagement portion is a regular octagon that has eight circular arcuate vertex portions and eight side portions. 
     
     
       14. A work pallet positioning and fixing device according to  claim 1 , wherein the regular polygon that is the horizontal cross section of the tapered male engagement portion is a regular hexagon that has six circular arcuate vertex portions and six side portions. 
     
     
       15. A work pallet positioning and fixing device according to  claim 1 , wherein the hydraulic cylinder comprises a multi-layer coned disk springs for driving the ball lock mechanism. 
     
     
       16. A work pallet positioning and fixing device according to  claim 1  or  claim 15 , wherein the hydraulic cylinder comprises a hydraulic pressure operation chamber to which hydraulic pressure is supplied for driving the ball lock mechanism to unclamp the hydraulic cylinder. 
     
     
       17. A work pallet positioning and fixing device according to  claim 1 , wherein each of the plurality of side portions in the horizontal cross section of the tapered male engagement portion is formed as a circular arc that bulges slightly outward. 
     
     
       18. A work pallet positioning and fixing device according to  claim 1 , wherein each of the plurality of side portions in the horizontal cross section of the tapered male engagement portion is formed in a rectilinear shape. 
     
     
       19. A work pallet positioning and fixing device according to  claim 1 , wherein each one side portion of the plurality of side portions in the horizontal cross section of the tapered female engagement portion comprises a concave relief portion formed at a central portion of said each one side portion, and a pair of close engagement portions formed at respective ends of the concave relief portion. 
     
     
       20. A work pallet positioning and fixing device according to  claim 1  or  claim 19 , wherein each of the plurality of side portions in the horizontal cross section of the tapered male engagement portion comprises a concave relief portion formed at a central portion, and a pair of close engagement portions formed at respective ends of the concave relief portion. 
     
     
       21. A work pallet positioning and fixing device according to  claim 1 , wherein said regular polygon of the tapered female engagement portion of the base member conforms to said regular polygon of the tapered male engagement portion of the ring member to restrain said rotation of the ring member with respect to the base member about the vertical axis.